液相烧结中液相成份对堇青石相变和陶瓷显微组织的影响

堇青石相的形成速度与烧结过程中是否出现液相以及液相的成份有很大关系。为搞清液相在堇青石陶瓷烧结过程中的作用 ,该文采用差热分析仪 (DTA)、 X射线衍射仪(XRD)以及扫描电子显微镜 (SEM)的测试手段 ,分析和比较了高熔点的稀土氧化物 Ce O2 和低熔点 K2 O对堇青石陶瓷烧结过程中的相变和显微组织的作用。发现 K2 O主要通过产生低粘度液相改善陶瓷致密度 ,它在促进中间相尖晶石、方石英向堇青石转化方面作用不大。相比之下 ,Ce O2 不仅能够降低堇青石的相变温度 ,特别是在玻璃相增加很少的情况下 ,大大加快堇青石的转化速度

Influence of liquid composition on the cordierite transformation and microstructure of cordierite ceramics during liquid sintering

The formation of cordierite is correlated with the occurrence of liquid phase and the additives in the sintering procedure of cordierite ceramics. Since CeO 2 (with high melting point) and K 2O (with low melting point) result in the liquid sintering, their effects on the phase transformation and microstructure of the ceramics were comparatively studied by differential thermal analysis (DTA), Xray diffractometer (XRD) and scanning electronic microscope (SEM). The results show that K 2O mainly increases the ceramic density by generating large amounts of lowviscous liquid phase before the cordierite transformation occurs, but has little effect on stimulating the transition of spinel and cristobalite to cordierite; the microstructure of the ceramics is composed of cordierite and large amounts of glass phase. In contrast, CeO 2 (mass fraction less than 0.03) has little effect on the ceramic density, because the liquid phase occurs after the solid diffusion transformation into cordierite. Although CeO 2 does not produce a large amount of liquid phase, it decreases the transformation temperature and accelerates the conversion rate towards cordierite.